Power washing your truck will NOT peal the plasti dip. I've had by bumpers and wheels done for over a year and done dozens of power washes and gone through multiple drive through washes, it will not come off. So go for it. Its cheap and if you don't like it, take it off. Just make sure to put it on nice and heavy. If your too thin, it will be a pain to peel.
And to all the people hating on plasti dip and saying if you can't do it right, then don't do it at all. Not all of us have to money flowing out of our a** to throw away, so we do what we can in the mean time. And like the OP says, he wants to see how it looks, and plasti dip is perfect for that.